Airports currently represent a bottleneck for ever heavier air traffic. The rise in their capacity brings about ever greater complexity of the network of runways, taxiways and boarding zones. Incidents where the aircraft follows paths that are not in accordance with the itinerary dispatched by ground control via the radio are therefore being witnessed ever more often. Of course, the possibilities of incidents increase in poor weather or in poor visibility conditions. It is therefore fundamental that the pilot of the aircraft knows very precisely where his aircraft is situated in the airport zone and that he is perfectly aware of the route that he will have to follow and the manoeuvres that he will have to perform.
From the pilot's point of view, the position of the aircraft in an airport zone is currently obtained by consulting the outside indications on or in the vicinity of the taxiing zones. This perception of the positioning is correlated with the indications of a view of “moving-map” type which displays the aircraft on a horizontal plan of the airport zone (view from above or “bird's eye” view). This display system uses location of the carrier by the position data charted by systems of “GPS” (Global Positioning System) type and/or the inertial platform of the craft. The error margins engendered by systems based on GPS systems are too large to direct the aircraft when taxiing in poor meteorological conditions due for example to dense fog or to heavy rain, which greatly reduce visibility.
To improve the perception of the environment, notably in conditions of poor visibility, use is made of systems of “EVS” (Enhanced Vision System) type based on presentations of video images taken by onboard cameras. These “EVS” systems which constitute a worthwhile visual aid present the drawback of not correlating the images provided with airport databases.
To improve the effectiveness of “EVS” presentations, systems have been developed comprising at one and the same time optical sensors and means for comparing the images arising from these sensors with information arising from airport databases. These systems are termed “ESVS”, standing for Enhanced Synthetic Vision System or “CVS” for Combined Vision System. One of the main objectives of these systems is the detection of runway lamps and then the recognition of shapes or patterns known by the term “pattern recognition” on the basis of geometric points or primitives arising from this detection. To ensure this detection in all weathers, the cameras of these systems can operate in various wavelength ranges from the visible to the near infrared so as to better differentiate the images of the runway lamps from the background image. The images arising from the optical sensors can also be combined in various ways or be mixed with synthesized information coming from the database. Matching with the information contained in the database makes it possible to enrich the images resulting from the optical system and to consolidate the position of the aircraft on the basis of the position in the image of the objects detected on the runway. Information about systems of this type will be found in U.S. Pat. Nos. 6,232,602, 6,373,055, 6,806,469 and 7,102,130.
U.S. Pat. No. 7,382,288 from the company Rockwell and Collins describes an onboard device presenting a view of the outside landscape on a Head-Up sight or “HUD”, standing for Head-Up Display, with a representation of the airport indicator panels, this device is based on a system comprising neither cameras nor correlation with a database BDD. Orientation on the airport is aided by displaying panels in the HUD. This device presents the major drawback of basing the representation on location information of “GPS” type that is not consolidated by outside vision, the precision not being sufficient to guide the aeroplane perfectly in all circumstances.
These systems make it possible to substantially improve the perception of the outside environment. However, the image proposed by these systems does not facilitate perception and validation of the trajectory to be followed by the pilot. Indeed, under conditions of reduced visibility, with the EVS view not containing the indication of the trajectory to be followed, the system presents the drawback for the pilot of having to correlate the trajectory represented for example on a view of “moving map” type with his EVS view optionally enriched. This results in an overload of work. The pilot must extract indices characteristic of the route to be followed so as to be able to verify that the patterns recognized by the recognition system do indeed correspond to the desired route. Thus, these systems do not make it possible either to automatically confirm that the aeroplane is indeed following a route or to generate alerts in case of deviation with respect to this route.